We have continued to focus our research studies on the etiology, immunology, pathology, molecular biology, biochemistry, protein chemistry, and molecular genetics of subacute progressive degenerative diseases of the nervous system. Particular emphasis is placed on a group of rare diseases which we have identified as the transmissible spongiform encephalopathies (TSEs). This group consists of four human diseases--kuru, Creutzfeldt-Jakob disease (CJD), Gerstmann-Straussler- Scheinker diseases (GSS), and fatal familial insomnia (FFI); and five diseases of animals--scrapie, transmissible mink encephalopathy (TME), chronic wasting disease of deer and elk (CWD), feline spongiform encephalopathy (FSE) and bovine spongiform encephalopathy (BSE). We have demonstrated that these diseases are cerebral amyloidoses caused by posttranslational modification of a specific host precursor sialoglycoprotein resulting in the formation of amyloid fibrils. The normal cellular protein is on chromosome 20 in humans and 2 in mice and the abnormal isoform is formed de novo. The human diseases occur sporadically (80%), iatrogenically (2%) or as autosomal dominent genetic/infectious diseases (10%). By molecular genetic procedures 28 point mutations have been identified which significantly increases the probability of the conversion of the cellular protein to an infectious polypeptide. This year we received 231 blood specimens which yielded the following results: 4/231 (1.7%) had 24 base pair deletions in the R3 R4 region; 2/231 (0.9%) had mutation at codon 178; 3/231 (01.3%) had mutations at codon 200; 2/231 (0.9%) had mutations at codon 210; 1/231 (0.4%) had a silent mutation at codon 115 and we identified a new mutation at codon 187. Eleven of the positive mutations were homozygous for methianine at codon 129.Detection of the 14-3-3 protein in CSF of patients with presumptive diagnosis of CJD continues to be the most sensitive and specific laboratory test to support the clinical diagnosis of spongiform encephalopathies. We now have successfully transmitted BSE to squirrel monkeys and capuchin monkeys and from these animals transmission has been possible to mice and hamsters. Six chimpanzees inoculated with three distinct strains of chimpanzee- adapted CJD (2 each) developed detectable 14-3-3 in their CSF just prior to onset of clinical signs; following lecophoresis all six developed rapidly progressive CJD in a much shorter incubation period apparently due to the stress of anesthesia and leucophoresis procedure. This tends to support our earlier observation that severe stress or head injury is associated with onset of CJD. Infectious prion protein was detected only in inguinal lymph nodes, eye, optic nerve, brain, and spinal cord of the chimpanzees. Other studies conducted include: (a) development of an altered method for converting the abnormal form of the prion protein from the cellular form; (b) production of recombinant PrP; (c) urinary protein analysis of specimens from CJD patients by 2-D gel electrophoresis. We also studied the range and sensitivity of more than 18 monoclonal or polyclonal anti-PrP antibodies against all known natural and experimental spongiform host ranges. - Prion diseases; cerebral amyloidosis; spongiform encephalopathies; slow infections